Air pollution — the silent killer in our midst

Polluted air is responsible for 7 million deaths each year.

From October 30 to November 1 the World Health Organization (WHO) is organizing the first “Global Conference on Air Pollution and Health” at its headquarters in Geneva, Switzerland.

The goal of the international convocation is the fight against air pollution, which is one of the main causes of premature death on a global level and is caused—albeit not exclusively—by anthropogenic sources, especially from industry, traffic, and even from domestic sources, such as heating or cooking.

Statistics from the World Health Organization

That the impact of air pollution must not be taken lightly is demonstrated by the data published last May by the United Nations special agency. It shows, for example, that nine out of ten people in the world breathe polluted air.

Called a silent killer, the polluted air we breathe causes around 7 million deaths a year worldwide according to WHO. One of the ingredients that makes atmospheric pollution very insidious is especially the notorious PM2.5 or “fine particulate,” which, with a diameter of less than 2.5 microns, can penetrate into the lungs and the cardiovascular system, causing serious diseases, such as cardiovascular disease or lung cancer.

According to estimates, in 2016 about 4.2 million deaths were caused by external air pollution, while internal pollution caused another 3.8 million deaths. With regard to internal or “domestic” pollution, it is estimated that still around 3 billion inhabitants of the planet—or more than 40 percent of the global population—do not yet have access to clean fuels and cooking systems at home.

“It is unacceptable that more than 3 billion people—mostly women and children—still breathe lethal fumes every day using polluting stoves and fuels in their homes,” said the WHO Director General, Ethiopian Tedros Adhanom Ghebreyesus, in a press release. More than 90 percent of the pollution-related deaths occur in low and middle income countries, especially in Africa and Asia.

City pollution

In the WHO database, which is currently the “most comprehensive in the world” on air pollution, data flows from 4,300 cities in 108 countries around the world. Data relating to concentrations of fine particles are collected, for example PM10 and the aforementioned PM2.5. The latter contains substances that constitute the greatest risks to human health — sulphate, nitrates and black carbon — as explained by the press release.

“Many of the world’s megacities exceed WHO’s guideline levels for air quality by more than 5 times, representing a major risk to people’s health,” said Maria Neira, director of the Department of Public Health, Social and Environmental Determinants of Health at WHO. She observed however “an acceleration of political interest in this global public health challenge.”

One of the world’s countries with the most dramatic levels of air pollution is China. Despite the progress made in the fight against smog, right in the Jingjinji Metropolitan Region — that is, the capital region including Beijing, the city of Tianjin, and the province of Hebei — the average annual value of PM2.5 far exceeds, by 90 micrograms (μg) per cubic meter, the threshold of 10 μg set by the WHO, related the newspaper Neue Zürcher Zeitung (October 8).

Diesel engines

Diesel engines consume relatively little energy and are also efficient, but they emit more quantities of nitrogen dioxide (NO2) and fine particles compared to other engines. Landing in the spotlight following the Dieselgate scandal, which shook German car manufacturer Volkswagen, many cities in the world have started banning cars with diesel-powered engines.

While the mayors of four capital cities worldwide—Athens, Mexico City, Madrid and Paris—announced at the C40 Mayors Summit 2016 conference, held in Mexico City in December 2016, that the circulation of diesel engines will be banned; also in February the German justice has given the green light to blocking vehicles fueled by diesel.

The Bundesverwaltungsgericht, that is, the federal administrative court based in Leipzig, has established that individual German cities—in this case Düsseldorf (capital of the State of North Rhine-Westphalia) and Stuttgart (capital of the State of Baden-Württemberg)—may prohibit the circulation of cars with older and more polluting diesel engines: those with the Euro 4 and Euro 5 homologation.

The subject of the blocking of diesel cars is very controversial in Germany and played an important role in the regional elections that took place on 28 October in Hesse, where Chancellor Angela Merkel’s coalition government suffered a devastating loss.

Asthma

The exhaust fumes of diesel engines are, due to the presence of NO2, related to the onset of asthma, but nitrogen dioxide isn’t the only culprit. A new study published on October 24 in the journal Environmental Health Perspectives has calculated how many people every year end up in an emergency room for attacks of asthma triggered by three pollutants (both anthropogenic and natural): nitrogen dioxide (NO2), ozone (O3) and finally PM2.5 particulate matter.

From the data collected by the team led by Susan Anenberg, of the Milken Institute School of Public Health in Washington DC, for example, it emerges that ozone concentrations each year cause 9 to 23 million visits to the ER, or from 8-20 percent of all asthma visits. PM2.5 on the other hand causes 5 to 10 million visits, and nitrogen dioxide from 0.4 to 0.5 million.

While 12-30 percent of all asthma attacks can be attributed to polluted air, almost half (48 percent) of emergency room visits for ozone-related asthma attacks and more than half (56 percent) of those for asthma attacks attributable to PM2.5 were recorded in Southeast Asia (including India) and in the western Pacific regions. As for Europe, the study suggests that ozone and PM2.5 were responsible for respectively 7-18 percent and 2-4 percent of all asthma emergency room visits in the region.

It is estimated that in 2015 approximately 358 million people suffered from asthma, of which 14 percent were children. The disease, as recalled by the study in the introduction, is the fourth cause of years of life lived with disabilities or so-called YLDs (Years Lived with Disability) in children aged 5-14 years, and the 16th cause of YLDs in all age groups.